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Subject: Re: [PATCH v2] io_uring: reduce latency by reissueing the operation
To:     Olivier Langlois <olivier@trillion01.com>,
        Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
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 <86a768ba44d3d2009c313bd2b7ddf25e2a3f4b5e.camel@trillion01.com>
From:   Pavel Begunkov <asml.silence@gmail.com>
Message-ID: <812e6da7-70cf-d42e-800c-1ea1f6bd33b7@gmail.com>
Date:   Sun, 20 Jun 2021 22:09:12 +0100
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On 6/20/21 10:05 PM, Olivier Langlois wrote:
> On Sun, 2021-06-20 at 20:56 +0100, Pavel Begunkov wrote:
>> On 6/20/21 8:05 PM, Olivier Langlois wrote:
>>>
>>>  
>>> -static bool io_arm_poll_handler(struct io_kiocb *req)
>>> +#define IO_ARM_POLL_OK    0
>>> +#define IO_ARM_POLL_ERR   1
>>> +#define IO_ARM_POLL_READY 2
>>
>> Please add a new line here. Can even be moved somewhere
>> to the top, but it's a matter of taste.
> 
> If you let me decide, I prefer to let them close to where they are
> used. There is so much data definitions in the heading section that I
> feel like putting very minor implementation details to it might
> overwhelm newcomers instead of helping them to grasp the big picture.

Oh yeah, I think any is fine. And there are others
happily living in this style, like FFS_ASYNC_READ

> but I will add an extra space as you request
>>
>> Also, how about to rename it to apoll? io_uring internal
>> rw/send/recv polling is often abbreviated as such around
>> io_uring.c
>> IO_APOLL_OK and so on.
> 
> no problem. I will.
>>
>>> +static int io_arm_poll_handler(struct io_kiocb *req)
>>>  {
>>>         const struct io_op_def *def = &io_op_defs[req->opcode];
>>>         struct io_ring_ctx *ctx = req->ctx;
>>> @@ -5153,22 +5156,22 @@ static bool io_arm_poll_handler(struct
>>> io_kiocb *req)
>>>         int rw;
>>>  
>>>         if (!req->file || !file_can_poll(req->file))
>>> -               return false;
>>> +               return IO_ARM_POLL_ERR;
>>
>> It's not really an error. Maybe IO_APOLL_ABORTED or so?
> 
> Ok.
> 
> 

-- 
Pavel Begunkov